1. Field of the Invention
The present invention relates generally to the field of semiconductor technology. More particular, the present invention relates to a method of fabricating a metal-oxide-semiconductor (MOS) device, which is suited for medium-voltage or high-voltage applications.
2. Description of the Prior Art
High-voltage metal-oxide-semiconductor (HVMOS) devices are widely used for many types of high-voltage circuits such as input/output circuits, CPU power supply circuits, power management systems, AC/DC converters, etc. The commonly seen HVMOS devices include lateral-diffused metal-oxide-semiconductor (LDMOS) devices and double-diffused drain MOS (DDDMOS) devices.
HVMOS devices need to sustain high voltages. Accordingly, the gate dielectrics of the HVMOS devices also need to sustain high gate-to-drain voltages. However, the prior art method of forming HVMOS devices has gate oxide corner thinning problem and time-dependent dielectric breakdown (TDDB) reliability issue.